Perinatal xenohormone exposure impacts sweet preference and submandibular development in male rats.

OBJECTIVE: To determine the effect of perinatal exposure to low doses of genistein and/or vinclozolin on submandibular salivary gland (SSG) development in juvenile and adult male rats and to establish a link with sweet preference. MATERIAL AND METHODS: Female rats received orally (1 mg kg(-1) body weight/day) genistein and vinclozolin, alone or in combination, from the first gestational day up to weaning. Sweet preference was assessed at weaning and in adulthood in male offspring; submandibular glands were then collected to study the morphogenesis and mRNA expression of steroid receptors, growth factors and taste related proteins. RESULTS: Exposure to genistein and/or vinclozolin resulted in a higher saccharin intake on postnatal day 25 (P < 0.05) linked to a higher number of pro-acinar cells (P < 0.01) and mRNA expression of progesterone receptor, growth factors and gustine (P < 0.01). These increases disappeared in adulthood, but mRNA expressions of sex hormone receptors and growth factors were strongly repressed in all treated groups (P < 0.01). CONCLUSION: Our findings confirm that the SSG are target for xenohormones and provide evidence that perinatal exposure to low doses of genistein and/or vinclozolin could simultaneously disrupt not only the salivary gland prepubertal development and sweet intake but also endocrine gene mRNA expression later in life.

Current benign prostatic hyperplasia treatment: impact on sexual function and management of related sexual adverse events.

Benign prostatic hyperplasia (BPH) is a common disease in older men that can lead to lower urinary tract symptoms (LUTS). Male sexual dysfunction is also an age-related condition. Epidemiological studies have confirmed an association between BPH/LUTS and sexual dysfunction in ageing men that is independent of the effects of age, other co-morbidities and lifestyle factors. Proposed pathophysiological mechanisms for BPH/LUTS-associated sexual dysfunction include the nitric oxide/cyclic guanosine monophosphate (NO/cGMP) pathway, rho-kinase and endothelin-1 activity, autonomic nervous system overactivity and the metabolic syndrome, and pelvic organ atherosclerosis. Both BPH/LUTS and sexual dysfunction can have a substantial negative impact on a man's quality of life. However, urologists and primary care physicians appear to under-recognise sexual dysfunction in men with BPH/LUTS. Current guidelines recommend alpha-blockers and 5-alpha reductase inhibitors, either alone or in combination, among appropriate medical treatment options for BPH/LUTS. Randomised, controlled trials demonstrate that these therapies can be associated with sexual adverse effects (AEs) such as loss of libido, erectile dysfunction and ejaculatory disorders. Sexual dysfunction should be fully evaluated in men requiring treatment for BPH/LUTS using validated questionnaires. Management of sexual dysfunction in men treated for BPH/LUTS should involve assessment of co-morbidities and concomitant medications, consideration of lifestyle interventions such as weight loss and increased physical activity to improve risk factors and, if necessary, introduction of pharmacotherapies. In addition, physicians should provide patients with proper counselling on the possible sexual AEs of medical therapies for BPH/LUTS and their impact on sexual satisfaction, while being aware of the possibility that counselling in itself is likely to influence reported rates of sexual dysfunction.

[Assessment model for evaluating the preparedness plan for COVID-19 in a tertiary care hospital]. / Modelo de evaluación del plan de respuesta frente a la pandemia de COVID-19 en un hospital de tercer nivel.

BACKGROUND AND PURPOSE: During the first wave of the epidemic caused by SARS-CoV-2, hospitals have come under significant pressure. This scenario of uncertainty, low scientific evidence, and insufficient resources, has generated significant variability in practice between different health organisations. In this context, it is proposed to develop a standards-based model for the evaluation of the preparedness and response system against COVID-19 in a tertiary hospital. MATERIALS AND METHODS: The study, carried out at the University Hospital of Vall d'Hebron in Barcelona (Spain), was designed in two phases: 1) development of the standards-based model, by means of a narrative review of the literature, analysis of plans and protocols implemented in the hospital, a review process by expert professionals from the centre, and plan of action, and 2) validation of usability and usefulness of the model through self-assessment and hospital audit. RESULTS: The model contains 208 standards distributed into nine criteria: leadership and strategy; prevention and infection control; management of professionals and skills; public areas; healthcare areas; areas of support for diagnosis and treatment; logistics, technology and works; communication and patient care; and information and research systems. The evaluation achieved 85.2% compliance, with 42 areas for improvement and 96 good practices identified. CONCLUSIONS: Implementing a standards-based model is a useful tool to identify areas for improvement and good practices in COVID-19 preparedness and response plans in a hospital. In the current context, it is recommended to repeat this methodology in other non-hospital and public health settings.

[Combined treatment of BPS with tamsulosin and finasteride : Literature review and prescription data]. / Kombinationsbehandlung des BPS mit Tamsulosin und Finasterid : Literaturübersicht und Verordnungsdaten.

Combined therapy of benign prostatic syndrome (BPS) with α1-blockers and 5α-reductase (5AR)-inhibitors is recommended according to two leading studies on doxazosin/finasteride and tamsulosin/dutasteride for all 10 in Germany possible combinations (five α1-blockers and two 5AR inhibitors). Because tamsulosin and finasteride predominate in the treatment of BPS in Germany, the role of the combination tamsulosin/finasteride and its scientific basis from clinical studies has been investigated. A pharmacoepidemiological extrapolation from receipts of pharmacy data centres showed a strong increase of the combination tamsulosin/finasteride since 2003. As a free combination, tamsulosin/finasteride beside the fixed combination tamsulosin/dutasteride accounts to about 50% of all α1-blocker/5AR-inhibitor combinations today. Clinical studies on tamsulosin/finasteride have been published including controlled studies of the combination and both monotherapies. The results of improvement of lower urinary tract symptoms (LUTS), maximum urinary flow rate (Qmax), prostate volume (PV) and prostate-specific antigen (PSA) as well as adverse events and drug safety are in agreement with the leading studies. However, results due to chance cannot be excluded because of deficiencies in study design. A reliable comparison of the risk of progression between tamsulosin/finasteride and both monotherapies is lacking completely. Because of the great coherence and continuous evaluation of available data of all combinations, and with the established strong class effect of monotherapies, a continuation of the therapeutic practice with the combination tamsulosin/finasteride is possible.

Effect of a new leuprorelin formulation on testosterone levels in patients with advanced prostate cancer.

BACKGROUND AND SCOPE: Leuprorelin is a well known luteinising hormone releasing hormone (LHRH) agonist. The drug is effective in the treatment of advanced prostate cancer and is well tolerated. This article reviews published literature (based on a search of PubMed, EMBASE and Biosis databases to the end of 2005) and other sources of data on a new formulation of leuprorelin acetate (Eligard) for use in the treatment of hormone-dependent advanced prostate cancer. This product takes advantage of a novel delivery system (Atrigel) which forms an implant in situ that is capable of delivering double doses of leuprorelin consistently to provide better, more sustained testosterone suppression compared with a microsphere leuprolide acetate formulation. Two formulations, 7.5 mg and 22.5 mg, are currently available with duration of action of 1 and 3 months, respectively. The 2-week stability at room temperature prior to mixing facilitates its use and reduces the potential for waste. FINDINGS: In clinical studies of the new leuprorelin acetate formulation reviewed here, all patients achieved testosterone levels < or = 50 ng/dL and up to 98% of patients showed levels comparable to those resulting from surgical bilateral orchidectomy (< or = 20 ng/dL). Both formulations showed minimal breakthroughs, defined as a rise in testosterone levels after reaching levels of 50 ng/dL. The safety profile is typical of LHRH agonists, with mild to moderately severe 'hot flushes' being the most common adverse event. The higher dose of 22.5 mg, with a volume of 0.375 mL is administered subcutaneously via a small 20G needle, causing little local discomfort. CONCLUSION: Prostate cancer remains a major cause of morbidity and mortality in older men. In the majority of cases, suppression of serum testosterone levels is very effective. The level of testosterone suppression is currently under debate, with ideal suppression levels ranging from 20 to 50 ng/dL. Not all LHRH agonist therapy achieves the same degree of testosterone suppression as bilateral orchidectomy. The new leuprorelin acetate (Eligard) appears to achieve a testosterone suppression of 20 ng/dL in 98% of patients, while maintaining a side effect profile comparable to other products in its class.

[Drug therapy for benign prostatic syndrome (BPS)]. / Medikamentöse Therapie des benignen Prostatasyndroms (BPS).

Alpha1-receptor blockers (alfuzosin, doxazosin, tamsulosin and terazosin), 5alpha-reductase inhibitors (dutasteride and finasteride) and combinations thereof are used in the drug treatment of benign prostatic syndrome. As before, there is still no evidence supporting the use of plant extracts, the use of anticholinergic substances alone or in combination with other BPS drugs is currently under investigation and should not be attempted outside of clinical trials. For all drugs the placebo effect is considerable. Accordingly, deviations from the recommended doses are rapidly associated with an activity loss over that of placebo. alpha1-Receptor blockers show a rapid onset of action and are slightly superior to 5alpha-reductase inhibitors with regard to the relief of symptoms. All alpha1-receptor blockers are similarly effective at adequate doses, however, quantitative differences are seen in the side effect profiles. 5alpha-reductase inhibitors also provide relief from BPS-associated symptoms with the relief being volume-dependent. Prostate volume-dependent complications of BPS (operation risk and risk of acute urine retention) can be reduced by 5alpha-reductase inhibitors. Long-term drug studies have demonstrated the superiority of combination therapies over monotherapies with alpha1-receptor blockers and 5alpha-reductase inhibitors in patients with a high risk for progression. This superiority is accompanied by a combination of the respective side-effect profiles and their absolute increase. Besides poorer tolerability, combination therapies also result in higher costs. Thus, it is important to decide at an early stage which patients are to be treated with drugs and which by surgery.

[S2e guideline of the German urologists: Conservative and pharmacologic treatment of benign prostatic hyperplasia]. / S2e-Leitlinie der Deutschen Urologen : Konservative und medikamentöse Therapie des benignen Prostatasyndroms.

This report summarizes the relevant aspects of the S2e guideline of the German Urologists for the conservative and pharmacological treatment of lower urinary tract symptoms due to benign prostatic hyperplasia. Recommendations are given regarding watchful waiting, behavioral therapy, phytotherapy and pharmacological mono- and combination therapy. The influence of the different therapeutic options on bladder outlet obstruction (BOO) is described in detail.

[S2e guideline of the German urologists: Instrumental treatment of benign prostatic hyperplasia]. / S2e-Leitlinie der Deutschen Urologen : Instrumentelle Therapie des benignen Prostatasyndroms.

This report summarizes the relevant aspects of the S2e guideline of the German Urologists for the instrumental treatment of the lower urinary tract symptoms due to benign prostatic hyperplasia. Recommendations are given regarding open and transurethral procedures (TUR-P, bipolar TUR-P, TUI-P, HE-TUMT, TUNA, and the different Laser techniques). Recommendations are also given concerning intraprostatic stents and injection therapies. The influence of the different therapeutic options on bladder outlet obstruction (BOO) is described in detail.

Integrating risk profiles for disease progression in the treatment choice for patients with lower urinary tract symptoms/benign prostatic hyperplasia: a combined analysis of external evidence and clinical expertise.

The RAND appropriateness method was used to explore the relevance of risk factors for disease progression in the treatment choice for patients with lower urinary tract symptoms/benign prostatic hyperplasia (LUTS/BPH). A total of, 12 international experts assessed the appropriateness of various treatments for 243 risk profiles. Highest appropriateness rates were found for alpha1-adrenoceptor antagonists (68% of profiles) and combination therapy (46%). A large prostate volume was the dominant argument in favour of 5alpha-reductase inhibitors and combination therapy, but was irrelevant for the choice of surgery. Considerable postvoid residual, severe symptoms and poor maximum flow rate were the most important factors in favour of surgery.

Risk factors for disease progression in patients with lower urinary tract symptoms/benign prostatic hyperplasia (LUTS/BPH): a systematic analysis of expert opinion.

Disease progression has become an important issue for the management of lower urinary tract symptoms/benign prostatic hyperplasia (LUTS/BPH). Although several risk factors have been identified, no specific patient risk profiles have been established that can be useful in the day-to-day management of LUTS/BPH. In this study, an international panel of urologists developed a risk classification based on the attribution of a risk score to 243 unique patient profiles. From the perspective of clinical decision making, it was concluded that postvoid residual, symptom severity and maximum flow rate are the most relevant determinants of the risk of disease progression.

Implication of cell kinetic changes during the progression of human prostatic cancer.

The daily percentage of cells proliferating and dying were determined for normal, premalignant, and cancerous prostatic cells within the prostate as well as for prostatic cancer cells in lymph node, soft tissue, and bone metastases from untreated and hormonally failing patients. These data demonstrate that normal prostatic glandular cells have an extremely low but balanced rate of cell proliferation and death (i.e., both <0.20%/day). This results in a steady-state, self-renewing condition in which there is no net growth, although the glandular cells are continuously being replaced (i.e., turnover) every 500 +/- 79 days. Transformation of these cells into high-grade prostatic intraepithelial neoplastic cells initially involves an unbalanced increase in the daily percentage of cells proliferating versus dying, such that net continuous growth occurs (i.e., mean doubling time, 154 +/- 22 days). As these early proliferation lesions continue to grow into late stage high-grade prostatic intraepithelial neoplastic cells, the daily percentage of cells dying increases further to a point equaling the daily percentage of proliferation. This results in cessation of net growth while inducing a 6-fold increase in the turnover time of these cells (i.e., 56 +/- 12 days), increasing their risk of further genetic changes. The transition of late stage high-grade prostatic intraepithelial neoplastic cells into localized prostatic cancer cells involves no further increase in proliferation but a decrease in death resulting in net continuous growth of localized prostatic cancers with a mean doubling time of >/=475 days. As compared to localized prostatic cancer cells, metastatic prostatic cancer cells within lymph nodes or bones of untreated patients have an increase in daily rate of proliferation coupled with a reduction in their daily percentage of cell death, producing net growth rates with a mean doubling time of 33 +/- 4 days and 54 +/- 5 days, respectively. Remarkably, there is no further increase in proliferation in hormonally failing patients, but instead an increase in the daily percentage of androgen-independent prostatic cancer cells dying within soft tissue or bone metastases. These changes result in doubling times which are two to three times longer (i.e., 126 +/- 21 and 94 +/- 15 days) in these lymph node and bone metastatic sites, respectively, compared to similar sites in hormonally untreated patients. These data demonstrate that the daily percentage of proliferation for either androgen-dependent or -independent metastatic prostatic cancer cells is remarkably low (i.e., <3. 0%/day), consistent with why antiproliferative chemotherapy has been of such limited value against such metastatic cells. These results also suggest that prostatic carcinogenesis starts in the second to third decade of life and may require over 50 years for progression to pathologically detectable metastatic disease.

[Drug therapy for benign prostatic hyperplasia. Systematic overview]. / Medikamentöse BPS-Therapie. Eine systematische Ubersicht.

5alpha-Reductase inhibitors and alpha(1)-receptor blockers are established options for symptomatic treatment of benign prostatic hyperplasia (BPH). Achieving maximum efficacy is contingent on correct dosage and requires careful patient selection in view of the substance class employed. All applicable preparations exert only a low-grade effect on prostatic obstruction. This condition should be excluded by appropriate urological examination before treatment is initiated. If the patient's distress is minor, refraining from drug therapy can be considered. Symptomatic patients with small prostate volume are suited for monotherapy with alpha(1)-receptor blockers and symptomatic patients with large prostate volume profit from combination therapy. When 5alpha-reductase inhibitors are used, BPH patients should be made aware of the findings from the Prostate Cancer Prevention Trial.

Dietary exposure in utero and during lactation to a mixture of genistein and an anti-androgen fungicide in a rat mammary carcinogenesis model.

Endocrine disruptors may play substantial roles in the high incidence of breast cancer. We previously described how early exposure to the mixture of phytoestrogen genistein (G) and the anti-androgen vinclozolin (V) affects peripubertal mammary development. This study evaluates the carcinogenic potential of exposure to V alone or associated with G from conception until weaning in Wistar rats. Dams were exposed to V, G or GV during pregnancy/lactation. At PND50 offspring were treated with DMBA[7,12-dimethylbenz(a)anthracene]. V or GV maternal exposure decreased number of DMBA-induced mammary tumors in the offspring, without significant modifications in tumor incidence, multiplicity and latency. G exposure decreased number of tumors, incidence and multiplicity. Unexpectedly, GV exposure increased tumor volume (p=0.04 vs controls) and epithelial proliferation (p=0.001 vs controls; p=0.005 vs G,V only). All tumors were in situ carcinomas. Concluding, maternal gestation/lactation exposure to a vinclozolin and genistein mixture significantly increases offspring tumor growth without changes in carcinogenesis susceptibility.

[Treatment mapping of prostate cancer in DVPZ prostate centers in Germany]. / Versorgungsabbild zum Prostatakarzinom in DVPZ-Prostatazentren in Deutschland.

BACKGROUND: In prostate centers of the Governing Body of German Prostate Centers (DVPZ, Dachverband der Prostatazentren Deutschlands e.V.) treatment data from 3 university clinics, 21 treatment clinics, 3 private clinics and 330 general practitioners incorporated under 22 certificates are collated, in order to document the quality and type of cross-sectoral and interdisciplinary treatment, in particular of prostate cancer (PCA) patients. METHODS: This analysis is based on the DVPZ UroCloud data sets from 20 July 2015. The UroCloud reflects the web-based chronological disease development and quality parameters. For the descriptive analysis of particular key figures, available complete data sets were selected. RESULTS: Of the centers 22 held a valid certificate and fulfilled all required case numbers and structural prerequisites at the primary certification or recertification. In three cases a reauditing led to requirements before certification. Since 2005 a total of 9650 PCA patients have been pseudonymized and followed up (41,247 follow-up forms, 4.3 forms per patient). In 2014 the median number of newly documented PCA patients was 61 per center (minimum 7 and maximum 295). Radical prostatectomy (RP) dominated with 4491 (56 %) cases followed by primary hormonal therapy (1210 cases, 15 %), irradiation (809, 10 %) and non-interventional therapy, such as active surveillance (AS) or watchful waiting (WW) in 760 cases (10 %). A prostate-specific antigen (PSA) reduction was documented in 50 % of the patients with a preoperative PSA value > 20, in 60 % of pT4 tumors and in 50 % of patients with a tumor Gleason score of 9-10. A positive incision margin (R+) was found in in 15 % of pT2 stages, 41 % of pT3 stages and 85 % of pT4 stages. A secondary intervention was documented in 6.5 % of RP. CONCLUSION: The DVPZ certificate reflects the complete spectrum of treatment of PCA patients. The strength of the certificate lies in the documentation of patient development and a simultaneous collation of quality parameters.

Induction of gamma GT- and GST-P positive foci in the liver of rats treated with 2-nitropropane or propane 2-nitronate.

2-Nitropropane (2-NP) or its anionic form propane 2-nitronate (P2-N) were tested as initiators in a sequential model of rat hepatocarcinogenesis, at the end of which preneoplastic foci were histologically detected. Six intraperitoneal (i.p.) injections of 25, 50 or 100 mg 2-NP or P2-N/kg body weight resulted in the appearance of liver gamma-glutamyltranspeptidase (gamma GT)- and glutathione S-transferase (GST-P)-positive foci, whose number and size increased with the dose of initiator. 2-NP and P2-N were equally effective. The potency of the highest dose (6 x 100 mg/kg body wt) was comparable to that of a single injection of diethylnitrosamine (100 or 200 mg/kg body wt). This work provides a short-term (70 days) and convenient model for further studies on 2-NP carcinogenicity.

Modulation of aflatoxin B1 carcinogenicity, genotoxicity and metabolism in rat liver by dietary carotenoids: evidence for a protective effect of CYP1A inducers.

The effects of several carotenoids of vitamin A and of 3-methylcholanthrene have been tested on the initiation of hepatocarcinogenesis by aflatoxin B1, using the sequential protocol of Solt and Farber. AFB1-induced DNA single-strand breaks and AFB1-metabolism were also assessed. The P4501A inducer carotenoids (canthaxanthin, astaxanthin, beta-apo-8'-carotenal) and 3-methylcholanthrene reduce the carcinogenicity of AFB1, divert AFB1-metabolism into the less genotoxic aflatoxin M1 and reduce AFB1-induced DNA single-strand breaks: we conclude that these carotenoids exert their protective effect through the deviation of AFB1 metabolism towards detoxification pathways. beta-Carotene decreased AFB1 carcinogenicity but did not alter its metabolism, probably acting by other mechanisms.

Determination and characterization of diuretics in human urine by liquid chromatography coupled to pneumatically assisted electrospray ionization mass spectrometry.

The aim of this work was to develop a method for the characterization and determination of diuretics in human urine samples by liquid chromatography (LC) coupled to pneumatically assisted electrospray ionization (ES) mass spectrometry (MS). The diuretics studied were substances forbidden by the IOC such as trichlormethiazide, furosemide, canrenoic acid, benzthiazide, bendroflumethiazide, bumetanide, etacrynic acid and spironolactone. For this purpose, the operational parameters of electrospray, such as counter electrode voltage, capillary voltage, sample cone voltage and source temperature, were optimized in order to obtain the best signal stability and the highest sensitivity for the greatest number of diuretic agents. The optimized separation method was successfully coupled with the MS system to analyze the above-mentioned diuretics extracted from spiked urine samples by a liquid extraction and clean-up procedure at basic pH, using ethyl acetate as solvent and the salting-out effect (NaCl). The mass spectra obtained provide adequate information for identification purposes. Positive urine samples obtained from athletes were also analyzed. The presence of these substances in human urine was confirmed by this method, making LC/ES-MS an analytical tool to be considered in the area of antidoping control.

Androgen regulation of programmed death of normal and malignant prostatic cells.

Androgen-dependent normal prostatic glandular cells and androgen-dependent prostatic cancer cells can be induced to undergo cell death after androgen ablation. This death does not require the cells to proliferate and occurs as an energy-dependent process collectively referred to as "programmed cell death" in which the cells actively commit "suicide." Associated with this programmed cell death pathway is the enhanced expression of a series of genes and the fragmentation of the genomic DNA into nucleosomal oligomers. This genomic DNA fragmentation is the irreversible commitment step in the death of the cell and results from activation of Ca2+/Mg(2+)-dependent endonuclease activity within the cell nucleus. This activation is due to sustained elevation of intracellular free Ca2+ (Cai) induced after androgen ablation. Metastatic prostatic cancer within an individual patient is heterogeneous, including both androgen-dependent and -independent cancer cells. Thus, androgen ablation is rarely curative since it only induces the programmed death of the androgen-dependent cancer cells without activating this pathway in the androgen-independent cancer cells within the patient. Androgen-independent prostatic cancer cells do not activate this death process after androgen ablation, since this does not induce a sustained increase in Cai. A new approach to treat androgen-independent prostatic cancer cells has focused on the use of chemotherapeutic agents to induce a sustained increase in Cai. These studies demonstrate that if such a sustained elevation in Cai is maintained, even androgen-independent prostatic cancer cells undergo programmed cell death.

Modelling retention in liquid chromatography as a function of solvent composition and pH of the mobile phase.

The aim of this work was to develop a model that accurately describes retention in liquid chromatography (LC) as a function of pH and solvent composition throughout a large parameter space. The variation of retention as a function of the solvent composition, keeping other factors constants, has been extensively studied. The linear relationship established between retention factors of solutes and the polarity parameter of the mobile phase, E(N)T, has proved to predict accurately retention in LC as a function of the organic solvent content. Moreover, correlation between retention and the mobile phase pH, measured in the hydroorganic mixture, can be established allowing prediction of the chromatographic behavior as a function of the eluent pH. The combination of these relationships could be useful for modelling retention in LC as a function of solvent composition and pH. For that purpose, the retention behavior on an octadecyl silica column of a group of diuretic compounds covering a wide range of physico-chemical properties were studied using acetonitrile as organic modifier. The suggested model accurately describes retention of ionizable solutes as concomitant effects of variables included and is applicable to all solutes studied. We also aimed to establish an experimental design that allows to reproduce to a good approximation the real retention surface from a limited number of experiments, that is from a limited number of chromatograms. Ultimately, our intention is to use the model and experimental design for the simultaneous interpretive optimization of pH and proportion of organic solvent of the mobile phase to be used in the proposed separation.

Retention behaviour of quinolone derivatives in high-performance liquid chromatography. Effect of pH and evaluation of ionization constants.

This paper examines the effect of solute ionisation on the retention behaviour of a series of quinolones and evaluates their pKa values using chromatographic data in acetonitrile-water mixtures with acetonitrile percentages of 30, 35, 40 and 50% (v/v). We also compare these pKa values with those previously obtained in acetonitrile-water mixtures from potentiometric measurements. In doing so, the pH values were measured in the hydroorganic mixture, which was used as the mobile phase, instead of in water, taking into account the effect of activity coefficients. The resulting equations permit the chromatographic determination of the pKa values of the quinolones in acetonitrile-water mixtures and also permit the prediction of the effect of pH on their chromatographic behaviour. These equations can be combined with those previously derived, which relate retention to the solvent composition of the mobile phase, to establish a general model that relates the elution behaviour of the solute to significant mobile phase properties: composition, pH and ionic strength.